13.Starling Co. is considering disposing of a machine with a book value of $21,200 and estimated remaining life of five years. The old machine can be sold for $5,300. A new high-speed machine can be purchased at a cost of 71,200. It will have a useful life of five years and no residual value. It is estimated that the annual variable manufacturing costs will be reduced from $23,000 to $20,700 if the new machine is purchased. The differential effect on income for the new machine for the entire five years is

a.increase of $54,400

b.decrease of $54,400

c.decrease of $70,720

d.increase of $70,720